The present invention relates to a cutting tool and in particular to a cutting tool, such as a router bit, used to trim plastic laminates. In the past, flush or bevel trimming of laminated plastic was accomplished by using a carbide tipped router bit. Such router bits typically include a steel ball bearing guide assembly beneath the cutting portion of the router bit.
When finishing cabinets, countertops, etc., a core material, for example plywood, chip board, or particle board is covered with a plastic sheet side apron as well as a plastic sheet top which overhangs the laminated side apron. These plastic sheets are typically fixed to the core material with adhesive. Often, before hardening, this adhesive material is forced from beneath the sheet, past the edge of the sheet, to the side and top of the sheet where it then hardens.
When trimming or removing the overhanging (i.e., excess) portion of the top sheet, a cutting tool such as a router bit is used to trim the excess material. A steel ball bearing guide assembly disposed closely beneath the cutting portion of the bit is employed as a guide and rolls along the side apron thereby ensuring that the edge of the top sheet is flush with the side apron sheet. However, due to the friction resulting from this trimming operation, the temperature of both the cutting tool and the material becomes elevated. This increase in temperature causes previously hardened adhesive to become soft and more fluid. It has been found that such soft adhesive sometimes flows down onto the outer radial surface of, and into, the ball bearing guide assembly. When the adhesive rehardens, the ball bearing guide becomes ineffective and, as a result, the edge of top sheet being trimmed will not be smooth and flush with the side apron sheet.
Thus, there is a need to provide a cutting tool such as a router bit for use in the above described applications in which the ball bearing guide assembly is protected from softened adhesive.